The data contained in these files contain topographic data collected by the CHARTS
system along Lake Michigan, Indiana. The data are broken into boxes. The box layout
index is provided by the shape file, "in_boxes.shp", and the box numbers for labels
are in the "Box" field of the shape file. The data file names are based on the year,
project, area name, box number, and product type. An example of the file name is "2008_NCMP_IN_Michigan_07_02DS08070_006_080916_1955_A_00452.las."
The 14th digit within the file name corresponds with the box names used. The data
was collected and processed in geographic coordinates and ellipsoid heights. The positions
are relative to NAD83 in decimal degrees of longitude and latitude. The heights were
converted from ellipsoid to orthometric heights using the Geoid03 model with the results
in meters. The date and time of each point are also MM:SS.SSSSSS. The format of the
file is LAS version 1.0

DOC/NOAA/NOS/OCM > Office for Coastal Management, National Ocean Service, National
Oceanic and Atmospheric Administration, U.S. Department of Commerce

Date(s)

publication: 2011-05-31

Data Presentation Form:

Digital image

Dataset Progress Status

Complete

Data Update Frequency:

As needed

Purpose:

These data were collected as a part of the NCMP to depict the elevations ABOVE AND
BELOW the water for the First Return OR Last Return OR Hydro in the Illinois coastal
zone.

Use Limitations

These data depict the elevations at the time of the survey and are only accurate for
that time. Users should be aware that temporal changes may have occurred
since this data set was collected and some parts of this data may no longer represent
actual surface conditions. Users should not use this data for critical
applications without a full awareness of its limitations. Any conclusions drawn
from analysis of this information are not the responsibility of NOAA or any of its
partners. These data are NOT to be used for navigational purposes.

These data were collected using the CHARTS surveys system. It is owned by the Naval
Oceanographic Office and Operated through contract. The system collects topographic
lidar data at 20kHz and hydrographic data at 3kHz. The system also collects RGB imagery
at 1Hz. A CASI-1500 hyperspectral line scanner is integrated with the system as well.
Aircraft position, velocity and acceleration information are collected through a combination
of Novatel and POS A/V equipment. Raw data are collected and transferred to the office
for downloading and processing in SHOALS GCS software. GPS data are processed using
POSPac software and the results are combined with the lidar data to produce 3-D positions
for each lidar shot. These data are edited using Fledermaus software where anomalous
data are removed from the dataset. The edited data are written to 5 km tiles along
the shoreline using chartsLAS, a program written by NAVO. This program reads data
from the original binary format files and produces separate ASCII files for first
and last return data. The data are converted from ellipsoid to orthometric heights,
based on the GEOID03 model, within the chartsLAS program.

The NOAA Coastal Services Center (CSC) received the data as unclassified files in
ASCII format. The files contained LiDAR intensity and elevation measurements. CSC
performed the following processing on the data for data storage and Digital Coast
provisioning: 1. The data were converted from ASCII to las format. 2. The data were
classified as 1 for the topo data (no bare earth) using the topo last (TL) elevation
and 11 for the hydro data. 3. The data were converted from NAVD88 heights to ellipsoid
heights using Geoid03. 4. The LAS header fields were sorted by latitude and updated.

Times had originally been stored as POSIX seconds when converted to LAS. This was
switched to adjusted GPS time (GPS seconds - 1e9) to conform to the LAS 1.2 standard.
The data were also converted to LAZ format.

The NOAA National Geophysical Data Center (NGDC) received lidar data files via ftp
transfer from the NOAA Coastal Services Center. The data are currently
being served via NOAA CSC Digital Coast at http://www.csc.noaa.gov/digitalcoast/.
The data can be used to re-populate the system. The data are archived in LAS or LAZ
format.
The LAS format is an industry standard for LiDAR data developed by the American Society
of Photogrammetry and Remote Sensing (ASPRS); LAZ is a loseless compressed version
of
LAS developed by Martin Isenburg (http://www.laszip.org/). The data are exclusively
in geographic coordinates (either NAD83 or ITRF94). The data are referenced vertically
to
the ellipsoid (either GRS80 or ITRF94), allowing for the ability to apply the most
up to date geoid model when transforming to orthometric heights.